tor-browser

The Tor Browser
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7zCrc.c (3237B)

      1 /* 7zCrc.c -- CRC32 init
      2 2017-06-06 : Igor Pavlov : Public domain */
      3 
      4 #include "Precomp.h"
      5 
      6 #include "7zCrc.h"
      7 #include "CpuArch.h"
      8 
      9 #define kCrcPoly 0xEDB88320
     10 
     11 #ifdef MY_CPU_LE
     12  #define CRC_NUM_TABLES 8
     13 #else
     14  #define CRC_NUM_TABLES 9
     15 
     16  #define CRC_UINT32_SWAP(v) ((v >> 24) | ((v >> 8) & 0xFF00) | ((v << 8) & 0xFF0000) | (v << 24))
     17 
     18  UInt32 MY_FAST_CALL CrcUpdateT1_BeT4(UInt32 v, const void *data, size_t size, const UInt32 *table);
     19  UInt32 MY_FAST_CALL CrcUpdateT1_BeT8(UInt32 v, const void *data, size_t size, const UInt32 *table);
     20 #endif
     21 
     22 #ifndef MY_CPU_BE
     23  UInt32 MY_FAST_CALL CrcUpdateT4(UInt32 v, const void *data, size_t size, const UInt32 *table);
     24  UInt32 MY_FAST_CALL CrcUpdateT8(UInt32 v, const void *data, size_t size, const UInt32 *table);
     25 #endif
     26 
     27 typedef UInt32 (MY_FAST_CALL *CRC_FUNC)(UInt32 v, const void *data, size_t size, const UInt32 *table);
     28 
     29 CRC_FUNC g_CrcUpdateT4;
     30 CRC_FUNC g_CrcUpdateT8;
     31 CRC_FUNC g_CrcUpdate;
     32 
     33 UInt32 g_CrcTable[256 * CRC_NUM_TABLES];
     34 
     35 UInt32 MY_FAST_CALL CrcUpdate(UInt32 v, const void *data, size_t size)
     36 {
     37  return g_CrcUpdate(v, data, size, g_CrcTable);
     38 }
     39 
     40 UInt32 MY_FAST_CALL CrcCalc(const void *data, size_t size)
     41 {
     42  return g_CrcUpdate(CRC_INIT_VAL, data, size, g_CrcTable) ^ CRC_INIT_VAL;
     43 }
     44 
     45 #define CRC_UPDATE_BYTE_2(crc, b) (table[((crc) ^ (b)) & 0xFF] ^ ((crc) >> 8))
     46 
     47 UInt32 MY_FAST_CALL CrcUpdateT1(UInt32 v, const void *data, size_t size, const UInt32 *table)
     48 {
     49  const Byte *p = (const Byte *)data;
     50  const Byte *pEnd = p + size;
     51  for (; p != pEnd; p++)
     52    v = CRC_UPDATE_BYTE_2(v, *p);
     53  return v;
     54 }
     55 
     56 void MY_FAST_CALL CrcGenerateTable()
     57 {
     58  UInt32 i;
     59  for (i = 0; i < 256; i++)
     60  {
     61    UInt32 r = i;
     62    unsigned j;
     63    for (j = 0; j < 8; j++)
     64      r = (r >> 1) ^ (kCrcPoly & ((UInt32)0 - (r & 1)));
     65    g_CrcTable[i] = r;
     66  }
     67  for (i = 256; i < 256 * CRC_NUM_TABLES; i++)
     68  {
     69    UInt32 r = g_CrcTable[(size_t)i - 256];
     70    g_CrcTable[i] = g_CrcTable[r & 0xFF] ^ (r >> 8);
     71  }
     72 
     73  #if CRC_NUM_TABLES < 4
     74  
     75  g_CrcUpdate = CrcUpdateT1;
     76  
     77  #else
     78 
     79  #ifdef MY_CPU_LE
     80 
     81    g_CrcUpdateT4 = CrcUpdateT4;
     82    g_CrcUpdate = CrcUpdateT4;
     83 
     84    #if CRC_NUM_TABLES >= 8
     85      g_CrcUpdateT8 = CrcUpdateT8;
     86  
     87      #ifdef MY_CPU_X86_OR_AMD64
     88      if (!CPU_Is_InOrder())
     89      #endif
     90        g_CrcUpdate = CrcUpdateT8;
     91    #endif
     92 
     93  #else
     94  {
     95    #ifndef MY_CPU_BE
     96    UInt32 k = 0x01020304;
     97    const Byte *p = (const Byte *)&k;
     98    if (p[0] == 4 && p[1] == 3)
     99    {
    100      g_CrcUpdateT4 = CrcUpdateT4;
    101      g_CrcUpdate = CrcUpdateT4;
    102      #if CRC_NUM_TABLES >= 8
    103      g_CrcUpdateT8 = CrcUpdateT8;
    104      g_CrcUpdate = CrcUpdateT8;
    105      #endif
    106    }
    107    else if (p[0] != 1 || p[1] != 2)
    108      g_CrcUpdate = CrcUpdateT1;
    109    else
    110    #endif
    111    {
    112      for (i = 256 * CRC_NUM_TABLES - 1; i >= 256; i--)
    113      {
    114        UInt32 x = g_CrcTable[(size_t)i - 256];
    115        g_CrcTable[i] = CRC_UINT32_SWAP(x);
    116      }
    117      g_CrcUpdateT4 = CrcUpdateT1_BeT4;
    118      g_CrcUpdate = CrcUpdateT1_BeT4;
    119      #if CRC_NUM_TABLES >= 8
    120      g_CrcUpdateT8 = CrcUpdateT1_BeT8;
    121      g_CrcUpdate = CrcUpdateT1_BeT8;
    122      #endif
    123    }
    124  }
    125  #endif
    126 
    127  #endif
    128 }